News M.2 NVMe SSD Support Comes to DSLR Cameras

So the justification is that it is cheaper than Compact Flash? That is a poor reason to add something that sticks out, breaking any weather proofing as well as add potential to break the camera storage door and/or slot.

OP think you mean drives not drivers:
In most cases, PCIe 3.0 drivers are cheaper than CFexpress cards, and you get access to higher capacities with the former at lower prices.
 
So the justification is that it is cheaper than Compact Flash? That is a poor reason to add something that sticks out, breaking any weather proofing as well as add potential to break the camera storage door and/or slot.

OP think you mean drives not drivers:
CFexpress, not Compact Flash. Two different form factors, two different interfaces.
'Sticking out with the flaps open' is the standard operating condition for DSLRs (rare nowadays), MILCs and prosumer ILC video cameras (e.g. Sony FX3, Sigma FP, the ubiquitous BMPCCs), used for video recording. These are operated within a cage with a pile of miscellaneous equipment bristling from it such as external battery power, mics, video monitors, recorders, etc. Adding an extra mount for an SSD cage is not a major burden, and if it allows slapping in a series of inexpensive 2TB m.2 SSDs that perform just as well as a $1000+ CFExpress card (or 8TB SSDs that have no CFExpres equivalent) then it could be very attractive indeed.